Department of Safety Engineering, Faculty of Engineering Yokohama National University
156 Tokiwadai, Hodogaya-Ku, Yokohama 240, Japan. - p. 493-502.
There are several flammable gases used in semiconductor industries, and some oxidizing
gas such as chlorine trifluoride (ClF3) is also used in the same production apparatus As
knowledge of the combustion characteristics of flammable gases with oxidizing gases other
than oxygen are lacking, an experimental study to evaluate combustion characteristics was
performed. Chlorine trifluoride, the oxidizing gas used in this study was commercialized
recently for etching and cleaning purposes because of its powerfid oxidizing ability. These gases are toxic, except for hydrogen, and have high reactivity, so these gases were
first diluted with nitrogen separately The diluted TEOS and ammonia gases were found
to ignite spontaneously while being mixed with the diluted ClF3 gas. On the other hand,
the diluted hydrogen gas could be mixed with the diluted ClF3 gas without spontaneous
ignition. And a H2/ClF3/N2 mixture could be ignited by an electric spark Therefore, for
TEOS and ammonia, "flammable limit" means the limit of spontaneous combustion, and
for hydrogen the flammable limit means the usual limit of ignitability by an external ignition
source. The flammability diagrams of TEOS/ClF3/N2, NH3/ClF3/N2 and H2/CIF3/N2 mixtures
were determined. And reaction kinetics between them were discussed from observed
combustion characteristics.
